Pressurized clamp for securing tools or workpieces

Abstract

A pressurized or hydraulic clamp, with piston reset, for securing tools or workpieces, such as grinding wheels, milling tools, and the like, to a shaft. By pressurizing with a hydraulic fluid, a floating piston is pressed out of the clamping unit to hold the workpieces or tools against a support. In order to retract the piston when the hydraulic pressure is released, the circular piston is provided with a bead on its outside or inside, depending upon the application; the bead is connected to one or more springs. The springs, which are pre-tensioned in the starting position, and are further tensioned when the piston is driven out, automatically reset the piston when the pressure is released.

What I claim is: 
     
       1. A pressurized clamp having a longitudinal axis for securing tools or workpieces; said clamp having a front end and having a floating circular piston which is mounted at the front end for exerting pressure against said tool or workpiece to effect the securing thereof; said floating circular piston being adjustable axially toward said tool or workpiece by means of a pressurized fluid; the improvement in combination therewith which comprises: circular spring means for adjustably spring-loading said floating circular psiton biased symmetrically relative to the longitudinal axis of the clamp in a direction away from said tool or workpeice for automatically and uniformly moving said floating circular piston away from said tool or workpiece when hydrostactic pressure exerted by said pressurized fluid is released to effect return of said floating circular piston so that complicated and bothersome manipulations as to the return of said floating circular piston are avoided;   said piston being provided with contact means for said circular spring means; and   said circular spring means comprises at least one reset spring which acts against said contact means of said piston to spring-load the latter in the direction away from said tool or workpiece;   said contact means being an annular bead which is formed on the outer periphery of said piston and provides a radial contact surface for said at least one reset spring.   
     
     
       2. A clamp in combination according to claim 1, in which said reset spring is a cup spring, the radially inner portion of which acts aganist said bead of said piston. 
     
     
       3. A clamp in conbination according to claim 2, in which said cup spring is embodied on one piece as a retaining nut which is screwed onot said clamp. 
     
     
       4. A pressure-medium-actuated clamping device having a longitudinal axis and provided for axially securing tools or workpieces arranged upon a shaft, said clamping device including a clamping body having a front end and a threaded portion as well as also including therewith a floating circular piston mounted at the front end for exerting pressure against said tool or workpiece to effect axial adjustment via a pressure medium, comprising in combination therewith: a circular bead segment provided on said floating circular piston and having a radial cross section projecting symmetrically to the longitudinal axis of the clamping device, said circular bead segment having a radial circular engagement surface;   a circular spring means projecting radially as to said circular engagement surface and engaging against said circular engagement surface counter to the pressure medium; and   a retaining nut held under spring tension in engagement symmetrically relative to the longitudinal axis of the clamping device aganist said radial circular engagement surface of said floating circular piston, said retaining nut being adjustable in axial direction upon the clamping body with the threaded portion, said circular spring means being secured in such a way that with said floating circular piston in a starting position thereof there is applied a certain tension which is large enough to overcome friction of seals and the piston and which allows said floating circular piston to be reset into starting position thereof.   
     
     
       5. A clamping device in combination according to claim 4 in which said retaining nut and said spring means form a single unitary part. 
     
     
       6. A clamping device in combination according to claim 5 in which said spring means is a cup spring and said circular bead segment is arranged along an outer periphery of said floating circular piston.